(1) Field of the Invention
The present invention relates to a method of producing water-in-oil emulsion explosive (hereinafter, referred to as W/O emulsion explosive), and more particularly to a method of producing W/O emulsion explosive commercially advantageously in a short operation time by carrying out concurrently emulsification and kneading in one step.
(2) Description of the Prior Art
It is generally desired to decrease the number of production steps as small as possible in the commercial production of W/O emulsion explosive in view of the safeness in the production and the quality control of the resulting explosive regardless of the continuous method and batch method.
U.S. Pat. No. 4,138,281 specification discloses a method of producing W/O emulsion explosive comprising aqueous solution of inorganic oxidizer, oil, emulsifier and hollow microspheres. This method comprises five steps as illustrated in FIG. 1, that is, a step for conditioning an aqueous solution of inorganic oxidizer, a step for conditioning a mixture of oil and emulsifier, a step for preparing W/O emulsion by mmixing the mixture of oil and emulsifier with the above described aqueous solution of inorganic oxidizer, a step for kneading the resulting W/O emulsion together with hollow microspheres, and a step for packing the resulting W/O emulsion explosive.
Therefore, conventional methods for producing W/O emulsion explosive comprising such large number of steps is not desirable as a commercial production method.
There have been attempted various methods to carry out the above described emulsifying step and kneading step in one step. However, when a solid component of hollow microspheres is added to a W/O emulsion, the emulsion is broken, or the hollow microspheres are broken, and hence the W/O emulsion can not maintain its homogeneously emulsified state, and the quality of the resulting W/O emulsion explosive, particularly the storage stability thereof is deteriorated. As the result, the W/O emulsion explosive deteriorates in its detonability at low temperature or in its explosion performance during its storage for a long period of time.
The inventors have diligently studied for a long period of time in order to overcome the above described drawbacks, and have found out a method capable of concurrently carrying out the emulsification and kneading. Further, the inventors have ascertained that a W/O emulsion explosive produced by the newly found method has exactly the same explosion performance as that of a W/O emulsion explosive produced by the above described conventional method, wherein emulsification and kneading are carried out in separate steps, and have accomplished the present invention.